After you a little research, decide on which method of sharpening you want to use - electric, hand-held scraper-type, water stone, etc., go towww.leevalley.com
for a large selection of sharpening tools. I prefer their Japanese waterstones and a little gadget that clamps on the back of the knife to hold it at an exact angle to the stone you're using. It's adjustible for different angles, and is called "knife guide" in their catalog. Do a search for "sharpening" and you'll get the whole line of equipment. You will need a steel to maintain the edge. I like a diamond steel, but others prefer a steel steel.
If your library has a copy of Sharpening
by Leonard Lee (He's the Lee of LeeValley.) Read the chapter on knife sharpening and you will be able to decide just which approach you want to use. The book is mostly about woodworking tools, so it's probably not worth your money to buy it, but the knife chapter is excellent. Well, tho whole book is excellent, but you don't need most of it.
If it's not in the library and you could find a cheap used copy on Amazon, it might make sense. It'll tell you all you need to know.